Keywords

Graywater (Domestic wastewater) -- Florida, Sewage, Sewage -- Purification -- Florida, Sewage -- Purification -- Nutrient removal -- Florida, Urban runoff -- Florida, Water quality -- Florida, Water reuse -- Florida

Abstract

The subject of water scarcity and the rate of water consumption has become popular topics over the last few decades. It is possible that society may consume or contaminate much of the remaining readily available water if there is not a paradigm shift. This deep rooted concern has prompted investigations to identify alternative water use and treatment methods. Within this report, information is presented from the use of innovative water harvesting and on-site sewage treatment and disposal systems (OSTDS) at Florida’s Showcase Green Envirohome (FSGE.net), while also addressing low impact development (LID) practices. FSGE is a residential home that demonstrates methods that use less water and reduce pollution. Population increases have more than just an effect on the volume of water demanded. Adverse impacts on surface and groundwater quality are partially attributed to current design and operation of OSTDS. Nutrient loading from wastewater treatment systems may be a concern where numerous OSTDS are located within nutrient sensitive environments. Groundwater nitrate concentrations have been shown to exceed drinking water standards by factors of three or greater surrounding soil adsorption systems (Postma et al., 1992, Katz, 2010). As a contribution to efforts to reduce water use and improve water quality, this study investigates the viability and effectiveness of a residential integrated stormwater, graywater, and wastewater treatment system (ISGWTS) installed and operating for over a year at FSGE. ii Within this report is a continuation of results published previously that consisted of preCertificate of Occupancy (pre-CO) data and an optimization model at the Florida’s Showcase Green Envirohome (FSGE) in Indialantic, Florida (Rivera, 2010). This current report contains 12 months of post-CO data, along with data from bench scale models of the on-site septic treatment and disposal system (OSTDS). There are two main objectives of the study. The first objective is to quantify the performance of the passive treatment Bold & GoldTM reactive filter bed (FDOH classified “innovative system”) for nutrient removal. The second objective was to monitor the water quality of the combined graywater/stormwater cistern for non-potable use and assess the components (green roof, gutters, graywater piping). The performance of the passive innovative system is compared to past studies. Also a bench scale model that is constructed at the University of Central Florida (UCF) Stormwater Management Academy Research and Testing Lab (SMART Lab) is operated to provide data for two different retention times. Complex physical, biological, and chemical theories are applied to the analysis of wastewater treatment performance. The data from the OSTDS and stormwater/graywater cistern are assessed using statistical methods. The results of the OSTDS are compared to FDOH regulatory requirements for “Secondary Treatment Standards”, and “Advanced Secondary Treatment Standards” with promising results. The bench scale results verify that both nitrogen and phosphorus removal are occurring within the filter media and most likely the removals are due to iii biological activity as well as physiochemical sorption. The flow into the OSTDS has been reduced with the use of separate gray water system to only 29 gallons per person per day (gpcd). After the FSGE certificate of occupancy and for one year using the Bold & Gold Biosorption Activated Media (BAM), the TSS, BOD5, and CBOD5 are below the required 10 mg/L for the FDOH classified Advanced Secondary Treatment Systems. The effluent for the conventional drain field TSS, BOD5, and CBOD5 are above 10 mg/L (29.6, 35.7, and 29.0 mg/L). The effluent total nitrogen and total phosphorus for the innovative system are 29.7 mg/L and 4.1 mg/L, which are not low enough for the 20 mg/L nitrogen requirements, but are below the 10 mg/L phosphorus requirements. The conventional drain field has an effluent total nitrogen concentration of 70.1 mg/L and an effluent total phosphorus concentration of 10.6 mg/L, which both fail to meet FDOH Advanced Secondary Treatment requirements. The high nitrogen in the effluent can be attributed to high influent concentrations (about 3 times the average at about 150 mg/L). Longer residence times are shown to produce a removal greater than 90%. Also, nitrate average levels were below the 10 mg/L standard. The combined stormwater/graywater cistern is analyzed against irrigation standards. The graywater is filtered and disinfected with ozone to provide safe water for reuse. Nutrient concentrations are measured to compare with regulatory standards. For irrigation standards, salinity in the form of sodium, calcium, and magnesium are measured. Although high sodium adsorption ratio (SAR) and electrical conductivity (EC) values were recorded, their adverse iv impact on the vegetation has not been observed. . The only observed effect within the home to date is scale formation in the toilet. The use of potable water in FSGE is reduced to 41 gpcd using the integrated stormwater and graywater system. A minor volume of backup artesian well water was added to the cistern during the one year home occupancy phase. Based on less use of potable water and at the current potable water cost rate, the integrated stormwater and graywater system at FSGE will save the typical homeowner about $215 per year. If irrigation were used more often from the cistern, the cost savings in reduced potable water used for irrigation would increase the savings. The treatment cost for B&G BAM over a 40 year period of time based on a flow of 29 gpcd (as measured at FSGE) and for 4 persons is $2.07 per thousand gallons treated. The yearly cost of treatment is about $87.65. There is a reduction in potable water use estimated at 64% of the sewage flow (or 18.5 gpcd) which equates to about 27 thousand gallons in one year. The current average cost of potable water is $4.40 per thousand gallons. Based on reduced potable water usage, the savings per year are about $118.84. Thus the yearly savings in potable water cost ($118.84) offsets the cost of OSTDS treatment at FSGE for nutrient control ($87.65) using the data collected at FSGE. This comparison does not include the inflation cost of water over time. There is also an environmental preservation intangible cost (not quantifiable from this study) from reduced surface runoff and reduced pollutant discharges.

Notes

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Graduation Date

2011

Semester

Fall

Advisor

Chopra, Manoj

Degree

Master of Science in Environmental Engineering (M.S.Env.E.)

College

College of Engineering and Computer Science

Department

Civil, Environmental, and Construction Engineering

Degree Program

Environmental Engineering

Format

application/pdf

Identifier

CFE0004114

URL

http://purl.fcla.edu/fcla/etd/CFE0004114

Language

English

Release Date

December 2011

Length of Campus-only Access

None

Access Status

Masters Thesis (Open Access)

Subjects

Dissertations, Academic -- Engineering and Computer Science, Engineering and Computer Science -- Dissertations, Academic

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